powerpc/powernv: Check kzalloc() return value in pnv_pci_table_alloc

pnv_pci_table_alloc() ignores possible failure from kzalloc_node(),
this adds a check. There are 2 callers of pnv_pci_table_alloc(),
one already checks for tbl!=NULL, this adds WARN_ON() to the other path
which only happens during boot time in IODA1 and not expected to fail.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/pci.c

@@ -766,6 +766,9 @@ struct iommu_table *pnv_pci_table_alloc(int nid)
 	struct iommu_table *tbl;
 
 	tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL, nid);
+	if (!tbl)
+		return NULL;
+
 	INIT_LIST_HEAD_RCU(&tbl->it_group_list);
 	kref_init(&tbl->it_kref);